feat: add select to atom (#183)

paritytech · Aug 9, 2022 · 3fcd111 · 3fcd111
1 parent 52ea7d1
commit 3fcd111
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Showing 2 changed files with 11 additions and 4 deletions.
diff --git a/effect/sys/Atom.ts b/effect/sys/Atom.ts
@@ -1,4 +1,5 @@
-import { E_, Effect, Resolved, T_, ValCollection } from "./Effect.ts";
+import { select } from "../atoms/Select.ts";
+import { E_, Effect, Resolved, T_, Val, ValCollection } from "./Effect.ts";
 import { key } from "./key.ts";
 import { run, RunContext, RunResult } from "./run.ts";
 
@@ -23,6 +24,10 @@ export class Atom<N extends string, A extends unknown[], R>
     super(fqn);
   }
 
+  select(field: Val<keyof T_<this>>) {
+    return select(this, field);
+  }
+
   run(): RunResult<this> {
     return run(this);
   }

diff --git a/examples/those_of_subxt/read_era_rewards.ts b/examples/those_of_subxt/read_era_rewards.ts
@@ -1,8 +1,10 @@
 import * as C from "../../mod.ts";
 import * as U from "../../util/mod.ts";
 
-const activeEra = C.readEntry(C.polkadot, "Staking", "ActiveEra", []);
-const activeEraIndex = C.select(C.select(activeEra, "value"), "index");
-const eraRewardPoints = C.readEntry(C.polkadot, "Staking", "ErasRewardPoints", [activeEraIndex]);
+const idx = C
+  .readEntry(C.polkadot, "Staking", "ActiveEra", [])
+  .select("value")
+  .select("index");
+const eraRewardPoints = C.readEntry(C.polkadot, "Staking", "ErasRewardPoints", [idx]);
 
 console.log(U.throwIfError(await eraRewardPoints.run()));